Machining of three-dimensional microstructures in silicon by electrodischarge machining

Currently, nearly all microcomponents are fabricated by microelectronic production technologies like etching, deposition or other photolithographic techniques. In this way, the main emphasis has been put on surface micromechanics. The major challenge for the future will be the development of real three-dimensional microstructures. Electro-discharge machining (EDM) is a so-called non-conventional machining technique, whereby material is removed through the erosive action of electrical discharges (sparks) provided by a generator. As shown in this paper, EDM proves to be a versatile technique that is very well suited for machining complex microstructures. Several examples, especially microparts with three-dimensional features, are given. It is demonstrated that the EDM process is independent on the silicon crystal orientation. This means that a wafer can be machined in any direction with respect to the wafer's top plane. EDM, unlike most micromachining processes, is not a batch process. On the other hand, is it well situated to be used as a rapid prototyping technique or for machining complex parts. (C) 1998 Elsevier Science S.A. All rights reserved.